Training on mercury management and remediation of contaminated sites Human Health Risk Assessment Mercury contaminated sites Almadén, Spain. 18-19 November 2015
Definition A Human health risk assessment is the process to estimate the nature and probability of adverse health effects in humans who may be exposed to chemicals in contaminated environmental media, now or in the future (EPA)
Main objectives to determine tolerable levels of contaminants in soil and groundwater that are protective of public health and ecosystems: Site Specific Target Level (SSTL) to provide a consistent methodology for appraising and recording public health risks at contaminated sites to establish the baseline risks and determine whether site remediation is required (Decision-making) to enable the comparison of potential health impacts of various remedial technologies.
Tiers of analysis TIER 1 TIER 2 TIER 3 Screening level: comparison of known site data with published risk-based guidance levels, not considering local conditions Site-specific risk assessment and the development of sitespecific target levels for comparison with site data Site-specific risk assessment in more detail which may include statistical methods, mathematical modelling and the collection of additional data (e.g. Local epidemiologic study )
European soils policies EU Thematic Strategy for Soil Protection, adopted in 2006 Some countries: National policies for the management of contaminated sites Specific legislation regulating investigation and clean-up of contaminated land Proposal for a Directive of the European Parliament and of the Council establishing a framework for the protection of soil and amending Directive 2004/35/EC (may of 2014)
European soils policies Environment International, 2009
Spanish approach Royal Decree 9/2005 Risk-based Generic Values of Reference (GVRs) for 60 priority pollutants Site-specific risk assessment Risk-based Corrective Action Law 22/2011
Four-Step Process DATA EVALUATION Hazard identification Review key research to identify any potential health problems that a chemical can cause Determine the amount, duration, and pattern of exposure to the chemical Exposure assessment Toxicity assessment Estimate how much of the chemical it would take to cause varying degrees of health effects that could lead to illnesses Assess the risk for the chemical to cause cancer or other illnesses in the general population Risk characterization RISK MANAGEMENT AND DECISION-MAKING
Planning and research Step 0: Planning and Scoping Process and Data Evaluation Developing a Conceptual Site Model (CSM): is a representation of the physical, chemical and biological processes that control the transport, migration and actual/potential impacts of contamination (in soil, air, ground water, surface water and/or sediments) to human and/or ecological receptors. Factors to be considered: the contaminants: concentration, distribution and media affected, on and off the site physical characteristics of the environment characteristics of the exposed population means by which exposure could occur
CSM- Source On-Site Primary Source Off-Site Vapour phase Secondary Source Free phase (LNAPL) Dissolved phase Free phase (DNAPL)
SCM- Transport On-Site Wind erosion and Atmospheric dispersion Stormwater Off-Site Leaching to groundwater (from soils) Volatilisation and Atmospheric dispersion Volatilisation and Enclosed aaccumulation Mobile free-liquid migration Groundwater transport
CSM-Receptors Industrial use On-Site Future use? Sensitive ecosystem Off-Site Residential use Receptors
Step 1: Hazard Identification Process of determining whether exposure to a stressor can cause an increase in the incidence of specific adverse health effects (e.g., cancer, birth defects). It is also whether the adverse health effect is likely to occur in humans. Types of health effects: Acute effects Chronic threshold effects (all kinds of chronic toxicity other than cancer) Chronic cancer effects Source of data: Statistically controlled clinical studies on humans and animals (more common) Epidemiological studies
Step 2: Exposure Assessment Estimation of the magnitude, frequency, extent and duration of exposures to contaminants The key elements of exposure assessment are: Analysis of contaminant releases (concentration) Identification of potential exposure pathways Estimation of exposure for each pathway Estimation of contaminant intake for each pathway Evaluate uncertainties
Exposure Pathway Flowchart SOURCE SOURCE AREA TRANSPORT MECHANISM EXPOSURE ROUTES RECEPTORS Above ground storage tank/piping Affected sub-surface soils Leaching & Groundwater Transport Groundwater Potable water use Commercial /Industrial workers Sources: Product storage Piping/Distribution Operations Waste Management Units Other Source Sources area: Surface soils Subsurface soils Dissolved groundwater plume NAPL Sediments Transport mechanism: Wind erosion & Atmospheric Dispersion Volatilization and enclosed space accumulation Leaching to groundwater transport Mobile NAPL migration Storm water/surface water transport Transport Exposure routes: Dermal contact Ingestion Inhalation of Particulate Inhalation of Vapours Potable water use (ingestion, cooking, showering, cleaning) Swimming Receptors Receptors: Residents Commercial or Industrial workers Construction workers Recreational users Relevant Ecological Receptors and Habitats
Step 3: Toxicity Assessment Defines toxicity and dose-response relationship for each contaminant of concern Literature-based research exercise. Sources of toxicity information (among others): World Health Organization sources IRIS (Integrated Risk Information Systems), USEPA Risk Assessment Information System (RAIS) International Agency for Research on Cancer (IARC) documents
Step 4 : Risk Characterization Information from the data collection, exposure and toxicity assessments is summarised and integrated. Three steps: Risk estimation Risk evaluation Sensitivity and uncertainty analysis
Step 4 : Risk Characterization Non-carcinogenic substances: Characterized by a threshold below which the body is able to cope with or recover from the exposure HI (Hazard Index)= HQ (Hazard Quotient) = Intake non-carcinogenic/ Reference Dose Factor HI >1 UNSAFE HI <1 SAFE Carcinogenic substances: There is no threshold and the effect of episodic doses accumulate. There is no zero risk if there is exposure at all IELCR = Intake carcinogenic x Slope Factor (SFo) of the Dose response curve IELCR = Individual Excess Lifetime Cancer Risk Acceptable threshold is 10-5 ( in Spain)
Mercury (Hg) Mercury exists in several forms: methylmercury and other organic compounds, elemental (metallic) mercury and inorganic mercury compounds.
Mercury (Hg) toxicity For exposed living organisms, the form of mercury affects: how available it is to cause effects within the body; how it moves around inside the body; how toxic it is; how it accumulates, is transformed and leaves the body; how it biomagnifies (builds up) along the food chain. There are important qualitative and quantitative differences in the toxicity of different species of Mercury (e.g. methylmercury and Hg 2+ ions). e.g. Cancer Risk (EPA): Elemental mercury: Group D, not classifiable as to human carcinogenicity Inorganic mercury: mercuric chloride, as a Group C, possible human carcinogen Methylmercury: Group C, possible human carcinogen
Mercury (Hg) main exposure assessment Environmental compartment Chemical forms Exposure pathways Tissue absorption Atmosphere Mercury Vapour Inhalation Pulmonary Atmosphere Mercury Metallic Dermic Skin Terrestrial food chain and water ingestion Inorganic Mercury Ingestion Gastrointestinal Aquatic food chain (fish) Organic Mercury/MeHg Ingestion Gastrointestinal
Software UMS System (Germany) Vlier-Humaan (Belgium) JAGG (Denmark) Arrikugest (Spain) ConSim (Great Britain) P20 RTW (Great Britain) CLEA (Great Britain) Risc-Human (The Netherlands) ROME (Italy) RBCA Tool Kit for Chemical Releases (USA): http://www.gsinet.com/en/software/rbca-tool-kit-for-chemical-releases-version-2-6e.html RISC (USA): http://www.groundwatersoftware.com/risc.htm
RBCA Tool Kit for Chemical Releases
RBCA Tool Kit for Chemical Releases
RBCA Tool Kit for Chemical Releases
RBCA Tool Kit for Chemical Releases
RBCA Tool Kit for Chemical Releases
RBCA Tool Kit for Chemical Releases
RBCA Tool Kit for Chemical Releases
THANK YOU FOR YOUR ATTENTION!!! Silvia de la Rosa López sdelarosa@emgrisa.es